SMA SI 4548-US - Manual (Page 137)

SMA America, LLC 14 Connecting External Sources
Operating Manual SI4548-6048-US-BE-en-20 137
The requirements of the generator and the utility grid demand different settings of the Sunny Island.
In a battery-backup system with generator, the Sunny Island needs a signal circuit via the DigIn input.
The DigIn input notifies the Sunny Island when the utility grid is feeding in.
The Sunny Island has one AC external source connection labeled AC2 Grid/Generator. With only
one external connection, the DigIn input is used to distinguish between the generator or line voltage.
If the DigIn input detects an open electric circuit, the Sunny Island is operated with grid parameters
and can feed excess current into the utility grid. When the DigIn input has a closed electric circuit the
Sunny Island recognizes that a generator is available.
When using a generator, install an automatic transfer switch which is able to switch from the utility
grid to the generator. This can be an automatic transfer switch (ATS) or a manual transfer switch. An
automatic transfer switch provides an automatic changeover between generator and utility grid. In the
event of a grid failure, no intervention by the operator is necessary.
Abrupt switching from the utility grid to the generator and vice versa can lead to the
destruction of the Sunny Island
• If an automatic switch is installed, make sure that it completely disconnects the Sunny Island
from the utility grid and from the generator for at least five seconds.
• If a manual switch is installed, leave the switch in the OFF position for at least five seconds
before switching to the new position.
• If no switch is installed, install a switch (see Technical Information „Sunny Island 4548-US /
5048-US / 6048-US: Grid Backup with Generator“ at www.SMA-America.com).